How to share common c# code

I wrote some code and realized they share similar logic. I am struggling to share the logic and welcome any suggestions.

public List<string> SendTemplateAsSampleEmail(MtaConnection mtaConnection, ICollection<EmailRecipient> recipients,
           SimpleContentDto renderedContent)
        {
            var errorStrings = new List<string>();

            // Get the list of branded values
            var fromAddress = BrandingHelper.GetFromAddressForSampleEmail(_httpContextBase);
            var replyToAddress = BrandingHelper.GetFromAddressForSampleEmail(_httpContextBase);
            var fromName = BrandingHelper.GetBrandName(_httpContextBase);

            // First send as in TGE
            if (!string.IsNullOrEmpty(renderedContent.HtmlText))
            {
                errorStrings.AddRange(SendTransactionalEmail(mtaConnection, recipients, renderedContent.HtmlText,
                    HtmlSubjectPrefixAsTge + renderedContent.Subject,
                    fromAddress, fromName, replyToAddress,
                    emailDomain: "bounce@bounce.myngp.com",
                    preHeader: null,
                    contentType: EmailContentType.HtmlContent));
            }
            return errorStrings;
        }
        public List<string> SendSampleEmailForHtmlContent(MtaConnection mtaConnection, ICollection<EmailRecipient> recipients, string name,
            string htmlContent, string preHeader)
        {
            return SendTransactionalEmail(mtaConnection, recipients, htmlContent, HtmlSubjectPrefix + name,
                fromAddress: BrandingHelper.GetFromAddressForSampleEmail(_httpContextBase),
                fromName: BrandingHelper.GetBrandName(_httpContextBase),
                replyToAddress: BrandingHelper.GetFromAddressForSampleEmail(_httpContextBase),
                emailDomain: "bounce@bounce.myngp.com", preHeader: preHeader,
                contentType: EmailContentType.HtmlContent);
        }